Electron discharge device having novel indirectly heated cathode mounting

ABSTRACT

A cathode stop provided externally of the electron cage reduces noise and microphonics generated by loose cathode structures. The stop is utilized in conjunction with a cantilevered mica tongue which exerts pressure on the cathode.

United States Patent Inventor William A. Allgaier Emporium, Pa.

July 16, 1969 Oct. 19, 1971 Sylvania Electric Products Inc.

Appl. No. Filed Patented Assignee ELECTRON DISCHARGE DEVICE HAVING NOVEL INDIRECTLY HEATED CATHODE MOUNTING 4 Claims, 3 Drawing Figs.

US. Cl 313/260, 313/261, 313/269, 313/281, 313/337 Int. Cl A47b 91/00, A47b 47/00 Field of Search 313/268, 269, 270, 261, 250, 260, 281, 337

References Cited UNITED STATES PATENTS 11/1957 Sweet 313/260X 2,820,919 1/1958 Wall .Q 313/269X 2,886,734 5/1959 Wittwer 313/260X 2,942,131 6/1960 Taylor... 3l3/260X 2,494,853 1/1950 Alma 3l3/269X FOREIGN PATENTS 258,022 7/1963 Australia 313/269 812,868 5/1959 0166181116111 313/269 1,306,006 9/1962 France 313/269 Primary ExaminerJohn W. Huckert Assistant Examiner-Andrew J. James Attorneys-Norman J. O'Malley, Donald R. Castle and William H. McNeill ABSTRACT: A cathode stop provided externally of the electron cage reduces noise and microphonics generated by loose cathode structures. The stop is utilized in conjunction with a cantilevered mica tongue which exerts pressure on the cathode.

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WILLIAM A. ALLGAIER AT TORNE Y ELECTRON DISCHARGE DEVICE HAVING NOVEL INDIRECTLY HEATED CATHODE MOUNTING BACKGROUND OF THE INVENTION This invention relates to electron discharge devices and more particularly to mounting structures for indirectly heated cathodes utilized therein. More specifically, it relates to indirectly heated cathodes which utilize a cantilevered tongue for applying continuous pressure to the cathode.

Previous electron discharge devices which utilized the pres- OBJECTS AND SUMMARY OF THE INVENTION 1 directly heated cathode.

These objects are accomplished in one aspect of the invention by the provision within an electron discharge device, having an envelope and upper and lower spaced-apart insulated members therein engaging interior walls of the envelope, of an indirectly heated cathode which has extremities which project through the upper and lower insulating members and which has a cathode connecting tab affixed as by welding to one of the extremities and a cathode stop affixed to the other of the projecting extremities of the cathode externally of the insulating member and in contact therewith. A pressure-applying tongue contacts the last-named end of the cathode.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional elevational view of an electron dischargedevice utilizing the invention;

FIG. 2 is a partial sectional view taken along the line 2-2 of FIG. 1; and

FIG. 3 is a perspective view illustrating an upper mica of the tube.

DESCRIPTION OF THE PREFERRED EMBODIMENTS For a better understanding of the present invention together with other and further objects, advantages and capabilities thereof, reference is made to the following specification and appended claims in connection with the above-described drawings.

Referring now to the drawings with greater particularity, in FIG. I there is shown an electron discharge device having an envelope 12 within which is mounted an electrode cage or mount 14. In this instance mount 14 is a tetrode comprised of an indirectly heated cathode 16, a control grid 18, a screen grid 19 and an anode 20 all suitably connected to terminal pins 21 extending through the glass envelope 12 as is well known. The electrode elements 16, 18, 19 and 20 are all held in proper spaced relationship to each other by upper and lower insulating members 22 and 24, respectively. These members are here shown as conventional material, namely mica, the members being provided with triangular teeth 26 which frictionally engage the inner walls of the envelope. The anode 20 is fixed in position between members 22 and 24 by twisting end tabs 28, 30, respectively on the top and bottom edges of the anode as is conventional in the art. The grids I8 and 19 are held in place by frictional contact of the side rods with both of the micas and also grid side rod swages and stops, not shown, but well understood in the art.

The novel cathode mounting arrangement comprises a cathode stop 32, fixed in this instance to the top extremity 34 of cathode 16. The lower extremity 36 has a cathode connectin tab 38 welded thereto and to a pin 21.

he cathode stop 32 is outside the mica cage and rests against the upper surface thereof under normal conditions. It comprises a metallic extension which in this instance is rectangular, and of a size larger than the width of the cathode sleeve so that it extends therebeyond. A cantilevered pressure-applying tongue 40 is positioned adjacent the top extremity 34 and has its free end overlying the cathode and exerting pressure thereupon. The pressure upon the cathode l6 and thus stop 32 forces thecathode, during heated operation, to first expand downwardly. This will cause the cathode tab 38 to give. If the expansion continues until the cathode tab 38 binds or cathode bead 41 contacts the bottom mica or otherwise is prevented from further downward increment, the pressure-applying tongue will yield upwardly a sufi'rcient amount to prevent the cathode from bowing. After shutofi' and subsequent cooling of the cathode 16 the tongue ensures that the cathode 16 will return to its normal position.

Thus, there has been provided by this invention a novel cathode mounting structure that reduces microphonics and resists bowing.

While there has been shown and described what is at present considered the preferred embodiment of the invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the scope of the invention as defined by the appended claims.

Iclaim:

1. In an electron discharge device having an envelope, upper and lower spaced-apart insulating members therein engaging interior walls of the envelope and supporting electrode elements therebetween, said elements having extremities which project above and below said members, one of said elements being an indirectly heated cathode having a connecting tab fixed to one of said projecting extremities, the improvement comprising: a cathode bead on said cathode adjacent the connecting tab but internally of said lower insulating member and spaced a given distance therefrom and a cathode stop affixed to the other of said projecting extremities externally of said upper member and in contact therewith at least while said device is inoperative, and means adjacent said extremity of said cathode containing said stop for applying pressure on said cathode to maintain said stop against said upper member,

whereby, during operation, the initial expansion of said 

1. In an electron discharge device having an envelope, upper and lower spaced-apart insulating members therein engaging interior walls of the envelope and supporting electrode elements therebetween, said elements having extremities which project above and below said members, one of said elements being an indirectly heated cathode having a connecting tab fixed to one of said projecting extremities, the improvement comprising: a cathode bead on said cathode adjacent the connecting tab but internally of said lower insulating member and spaced a given distance therefrom and a cathode stop affixed to the other of said projecting extremities externally of said upper member and in contact therewith at least while said device is inoperative, and means adjacent said extremity of said cathode containing said stop for applying pressure on said cathode to maintain said stop against said upper member, whereby, during operation, the initial expansion of said cathode from heating is directed downwardly until said cathode bead contacts said lower member and subsequent expansion is upwardly against said pressure-applying means.
 2. The invention of claim 1 wherein said means for applying pressure comprises a tongue of electrically insulating material.
 3. The invention of claim 2 wherein said material is mica.
 4. The invention of claim 1 wherein said cathode stop comprises an elongated metallic member affixed to said cathode and said cathode bead is formed as an integral part of said cathode. 